Preparing ferric articles for metallic baths



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' PREPARING FERRIG ARTICLES FOB METALLIC BATES.

No Drawing.

T 0 all whomit may concern Be it known that I, JAMEs lliVIADDY, a citizen of the United States, residing at 610 \Vest 116th street, New York, county of New York, and State of New York, have invented certain new and useful Improvements in Preparing Ferric Articles for Metallic Baths, fully described and represented in the following specification and the accom-, panying drawings, forming a part of the same. i

The present invention'relates to a means of protecting articles ofiron or-steel from corrosion by air, water, or acid fumes.

Ferric articles of sheet-iron or steel-plate, have often been dippedin molten lead to form a preservative coating thereon; but it is found that the protection afforded by such coating is far from perfect, as pin-holes or interstices are formed in the coating during the dipping operation through which, when putinto use, the atmosphereigradually gains access to the surface of the article and causes its corrosion.

-The .present invention prevents the formation f such defective coating when dipping in the lead bath, byfirst electro-plating a film of mercury upon the surface of the ar ticle, which mercury forms an amalgam with the iron or steel surface and covers it so thoroughly that the affinity of the lead.- for the amalgam enables the lead to adhere strongly to the article and form a continuous coatingand effective protection therefor.

The solution from which the mercury is electrically deposited upon thearticle should be an alkaline solution of mercury, Which 'may' be prepared in the proportion of 100 cubic centimeters of Water, one per cent. of cyanid of potassium, or other alkali; and from one to two per cent. of. mercuric cyanid.

Specification of Letters Patent. Patented Eiay 31,, 1921,

Application filed November 11, 1920. Serial No. 423,443. I

In practising the invention, the article is first thoroughly cleaned, as by a blast of steel grit "orin an acid bath,'and is then electro-plated Withmercury from the s0lution described.

When the film of mercury is deposited over the entire surface of the article, the article is immersed in the molten lead bath and the lead coating formed thereon.

I am aware that iron or steel articles have been dipped in a mercury cya'nid bath be- 'fore immersing them in a lead bath to form 'a lead coatingtbut an acid bath of mercury cyanid has always heretofore been used, although the acid in the'bath attacked the surface of the articles and impaired the uniformity of the lead coating subsequentlydeposited. 5

In the present invention an alkalinesolution of the mercury is employed which has no such effect upon the articles, and does not interfere with the uniform deposit of the mercury by an electroplating process.

The useof an alkaline mercury bath and the deposition of the mercuric film by elect'ro-plating distinguishes my invention from any previous use of mercur cyanid in the coating of iron or steel artic es.

Having thus set forth the nature of the invention what is claimed herein is:

The method of securing an effective continuous adhesion of lead coating to iron or steel articles in a molten bath, which consistsin electro-platin a film of mercury upon the surface of the article before dipping the article in the molten bath.

'In testimony whereof I have hereunto set my hand.

JAMES H. MAFDDY. 

